Thermostatic device.



PATENTBD JUNE 28, 1904. C. I'. HILKIER.

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THBRMOSTATIG DEVICE APPLIOATION FILED JAN. zz. 1904.

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UNITED STATES Patented June 28, ISO/.

PATENT CFFICE.

THERMOSTATIC DEVICE.

SPECIFICATION forming part of Letters VPatent No. 763,754, dated June28, 1904. Application filed January 22,1904. Serial No. 190,136. (Nomodel.)

To a/Z whom t 10m/y concern:

Be it known that I, CHRISTIAN FREDERI'K HILKIER, cand. phil., of 30 St.Hans Torv, Copenhagen, Denmark, have invented certain new and usefulImprovements'in or Relating `to Thermostatic Devices ParticularlyAdapted for Giving an Alarm in Case of Fire or of a Sudden Increase inTemperature, of which the following is a true description.

This invention relates to thermometers for indicating sudden increasesin temperature, such increase actuating an alarm device.

A thermometer according to this invention is illustrated by Way ofexample in the accompanying'drawing, in which it is shown in verticalsection.

A U-shaped tube a, preferably made of glass, contains as much mercury asis necessary to surround the platinum Wires b, Which are fused into thetube. In this Way the Wires are electrically connected, so that a Weakcurrent can pass to a sensitive relay. This relay is constructed in sucha manner that When the current is cut 0E its armature operates an alarmor closes an alarm-circuit. The branches c and CZ of the tube are sealedat the top. Both branches contain above the mercury some suitablevolatile liquid which has a determined boiling-point. The branch cor theliquid contained therein above the mercury could be made, if desired, ofdark color, so that it may absorb as many heat-rays as possible. Thebranch d is surrounded by a sleeve e or insulated from the outside airor radiant heat in some suitable Way. When the temperature risessuddenly, the liquid in the branch c will quickly begin to boil,or evenif it does not actually boil there will be a generation of gas orvapors. Pressure on the mercury in that branch Will therefore takeplace, so that the mercury in it will sink below the platinum Wires, thecurrent thus being broken. The relay will thereupon release itsarmature, and the alarm device Will be operated or the alarm-circuitclosed. The pressure on both columns of the liquid being very small,Which can be effected by exhausting from the branches of the tube beforesealing them all or nearly all the air, the counter-pressure in thebranch d will be thus very Weak when the liquid in c boils, and theliquid in (Z, owing tto its insulation, will not evaporate or at leastnot so quickly as the liquid in the branch c. Should the temperaturerise gradually, both the branches of the tube Will be gradually heatedto approximately the same extent. The thermometer will thus remaininoperative in case of gradual increase and will act only in case of asudden increase of temperature.

It Will be obvious that the apparatus described has also the advantagethat it regulates itself, as any leakage in any of the branches of thetube will result in a part of the mercury being forced from it into theother branch, and as the platinum Wires are arranged so that they dipinto the mercury only when it is approximately on the same level in bothbranches the leakage will be notified by the apparatus itself.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim isH l. Athermometer for indicating a sudden increase oftemperature, characterized by a U- shaped tube sealed at both ends, thebranches of the said tube being partially filled with mercury abovewhich is placed some volatile liquid, one branch being insulated fromradiant heat, While the other is adapted to be acted upon directly bysuch heat, substantially as described.

2. A construction of thermometer for indieating a sudden increase oftemperature, characterized by the branches of a U-shaped tube containingmercury, said mercury being ad apted to close an electric circuitthrough two platinum Wires arranged in the tube branches, the arms ofsaid tube being' sealed at the top, a partial vacuum or space filledwith rarelied air being situated in each branch above a liquid floatingin its turn on the mercury one tube branch or the liquid contained in itbeing dark colored, While the other branch is surrounded Withaheat-insulating sleeve or insulated in some other suitable mannersothat sudden changes of temperature affect the upper liquid inA thenon-insulated branch only substantially as described.

3. A thermometer comprising a sealed 100 tube, si body of mercury insaid tube, bodies body of mercury, electrical connections proA ot'volatile liquid in the tube at each end of jecting into the body ofmercury near each the mercury, electrical connections adapted to endthereof in combination with an insulatingbe connected by said mercury,and an insulsleeve surrounding one end of the said tube.

5 lating-covering surrounding a portion of the In Witness whereof I havehereunto set my 15 tube occupied by one of the bodies of volatile handin presence of two Witnesses.

liquid. CHRISTIAN FREDERIK HILKIER.

4. A thermometer comprising a sealed Witnesses: tube, a central body ofmercury therein, VIGGO C. EBERTH,

IO bodies of volatile liquid at each end of said MAGNUS J ENsEN.

